It is common to arrange for more than one class of cabins in an aircraft. In addition to the relatively densely packed economy class, there is usually a separate cabin area for premium class (or business class) with a lower seating density, giving a greater seating width and legroom to satisfy passengers who can afford a higher budget.
The configuration of such cabins, i.e. the proportion between economy class and premium class is often fixed and cannot be modified quickly and easily. It is, of course, the case that demand for seats in the economy class and that for seats in the premium class vary across different flights and different seasons. As one fixed configuration cannot fit all the flights or adapt to varying demands for premium seats and economy seats, an airline company cannot operate to maximize its profit.
Convertible seating units have been proposed. Such seating units may be converted into seat arrangements of different seating densities, usually by adjusting the width of the seats by varying the number of seats in each row. In addition, U.S. Pat. No. 6,715,716 discloses a seat assembly in which part of a back portion of a seat of a front row is movable to form a leg support for a seat of an adjacent rear row.
However, although more legroom is available in the seat assembly of U.S. Pat. No. 6,715,716 such is only suitable for sleeping posture, which a passenger may not wish to adopt during most of the flight time. For hygiene reasons, passengers may not wish to occupy a seat which can be converted into a leg support. In any event, thorough cleaning of the seat of the front row is a must. Furthermore, such prior art convertible seating units do not provide sufficient differentiation between the economy-class configuration and the business-class configuration.